Field of the Invention
The present invention relates to a photoelectric conversion apparatus and an image pickup system using a photoelectric conversion apparatus.
Description of the Related Art
A photoelectric conversion apparatus using a photoelectric conversion layer provided on a semiconductor substrate has been proposed. Japanese Patent Laid-Open No. 2012-064822 describes a photoelectric conversion apparatus that includes a photoelectric conversion layer provided for each pixel and disposed between an upper electrode and a lower electrode. The upper electrode and the photoelectric conversion layer described in Japanese Patent Laid-Open No. 2012-064822 extend to reach a pixel boundary portion and, therefore, a photoelectric convertible area has a high area occupancy in a single pixel (i.e., an aperture ratio is high). The lower electrode described in Japanese Patent Laid-Open No. 2012-064822 is provided to extend from the pixel boundary portion to the pixel boundary portion in the same manner as the upper electrode and the photoelectric conversion layer. Since the lower electrode constitutes a part of capacitance of the photoelectric conversion layer, the capacitance of the photoelectric conversion layer varies in accordance with the shape of the lower electrode. In the photoelectric conversion apparatus, in the case where capacitance for accumulation of charge in the photoelectric conversion layer is increased, noise (kTC noise) superimposed on photoelectrically converted signals may increase. The present invention reduces noise in the signals generated in the photoelectric conversion layer while maintaining the aperture ratio of the photoelectric conversion layer.